Embodiments presented herein generally relate to contactless energy transfer systems and, in particular, to contactless energy transfer for plug-in-hybrid and electric vehicles.
A typical motor vehicle with an internal combustion engine has a battery that is used predominantly for providing power to crank the engine to start the vehicle. Charging of the battery is usually done via an alternator driven by the engine. However, in a plug-in-hybrid or all-electric vehicle, the battery typically provides the power required to drive the vehicle, supplying energy to an electric motor coupled to a drive shaft of the vehicle. The battery in a plug-in-hybrid or all electric vehicle therefore typically needs to be charged from external source of electricity.
To date, most electric vehicle charging systems include contact based charging connectors having plug and socket connectors for contact-based charging. Contact based charging connector systems may have several disadvantages. For example, in outdoor applications, environmental impact may cause corrosion and damage of electrical contacts. Further, in view of the high currents and voltages often required to recharge electric vehicle batteries, establishing the physical connection for contact-based charging may involve cumbersome safety measures.
Contactless inductive charging systems are also available to charge electric vehicle batteries. Such systems often utilize a split core transformer configuration to avoid exposed electrical contacts. However, existing inductive charging systems often require that the coils of the transformer be held in close proximity during charging in order to achieve acceptable energy transfer efficiency, and this may result in reliability issues due to the small clearances between different parts of the charging system. Further, existing inductive charging systems are usually cord-based systems, thereby exhibiting the cord-related issues discussed above.